// Maybe 函子
class Maybe {
  static of(value) {
    return new Maybe(value);
  }

  constructor(value) {
    this._value = value;
  }

  map(fn) {
    return this.isNothing() ? Maybe.of(null) : Maybe.of(fn(this._value));
  }

  isNothing() {
    return this._value === null || this._value === undefined;
  }
}

class Container {
  static of(value) {
    return new Container(value);
  }
  constructor(value) {
    this._value = value;
  }
  map(fn) {
    return Container.of(fn(this._value));
  }
}

exports.Maybe = Maybe;
exports.Container = Container;
